The present invention relates to the field of multi channel imaging devices, and more particularly to projection type imaging devices, wherein it is very important to accurately align physical components of the apparatus such that the color components of a resulting image will be aligned. The predominant current usage of the present inventive multi channel imaging engine is as a component of projection video display devices, wherein it is desirable to have a rugged and accurately aligned electro-optical unit for projecting well aligned color images therefrom.
The typical arrangement for multi-channel imaging systems will have a clamshell arrangement where the internal optics and components are assembled from above and the optical cavity is split along a horizontal plane into two halves. However, the construction of such a device results in two or more assembly planes. For example, at least one is horizontal for the placement of the splitting and combining optics, and at least one is vertical for the placement of the projection optics. This requires complex molded parts with expensive tooling. Since there are two or more assembly planes, the registration of the optics becomes more difficult. This problem is made worse in an off-axis design where the optics are not all on the same plane.
It would be desirable to have a multi-channel imaging system wherein the alignment problems discussed above are ameliorated. It would be of further benefit if such a device were sufficiently rigid to prevent distortion problems caused by flexing and vibration. However, such a solution, in order to be practical, should be inexpensive to produce and inexpensive to use in the production of a final multi channel image projection system.
To the inventor""s knowledge, all previous apparatus or methods for producing a multi channel imaging engine have been difficult and/or expensive to manufacture and assemble, less than optimally rigid, and difficult to align and use.
Accordingly, it is an object of the present invention to provide a video projection engine that will provide sub-pixel accuracy over an entire image range.
It is still another object of the present invention to provide a video projection engine which is simple to construct and wherein components are readily aligned.
It is yet another object of the present invention to provide a video projection engine wherein there are no problems of mis-convergence due to twisting or bending of the optical housing.
It is still another object of the present invention to provide a video projection engine wherein artifacts from vibration introduced from external sources is minimized.
It is yet another object of the present invention to provide a video projection engine which is inexpensive to produce.
It is still another object of the present invention to provide a video projection engine which can be used with inexpensive auxiliary components.
It is yet another object of the present invention to provide a video projection engine which is inexpensive to install and align.
Briefly, an embodiment of the present invention is an assembly of mechanical components that aligns, supports and houses the optical, opto-mechanical and electronic components of a three color projection system. The architecture is executed in such a way that it solves many of the problems that are associated with high resolution multi-channel imaging systems. The total cost of the components is reduced because the number of components is less and the parts can be manufactured with high volume, low cost processes. The inter-channel stiffness and the mechanical stability between the individual color channels is superior to previous approaches. This is a direct consequence of the novel approach for enclosing the multi-channel cavity. There is no optical alignment required other than convergence of the discreet images. The components are all self-aligning with very low cost registration features.
The invention has a housing that is constructed in such a way that the entire optical cavity is contained inside the single formed part. The cavity is enclosed with a bulkhead that serves as a frame to align and support the optics and opto-mechanics. There is only a single assembly plane that is the plane of the bulkhead. The splitter and combiner optics are attached to the bulkhead as well as the projection lens. The cavity is enclosed when the kernel housing is attached to the bulkhead. The kernel housing can be formed as a single piece and there are no secondary operations required. The bulkhead can be stamped or molded and the bracket that holds the splitter dichroics, the combiner prism, the polarizer/analyzer assembly, and/or any additional optical devices can be molded (also with no secondary operations). There is a novel focussing mount for the projection lens that allows for a simple, low cost, fixed focus lens.
An advantage of the present invention is that a relatively inexpensive video projection engine is provided for incorporation into video projection imaging devices.
A further advantage of the present invention is that sub-pixel accuracy is provided over an entire image.
Yet another advantage of the present invention is that effects of vibration are essentially eliminated, such that cooling fans can be mounted on the video projection engine without adverse effects.
Still another advantage of the present invention is that the rigidity of the video projection engine essentially eliminates problems of mis-convergence due to twisting or bending of the optical housing.
Yet another advantage of the present invention is that the video projection engine is rugged in construction and reliable in operation.
Still another advantage of the present invention is that it is inexpensive to produce.
Yet another advantage of the present invention is that it is inexpensive to install, align, and use.
These and other objects and advantages of the present invention will become clear to those skilled in the art in view of the description of modes of carrying out the invention, and the industrial applicability thereof, as described herein and as illustrated in the several figures of the drawing. The objects and advantages listed are not an exhaustive list of all possible advantages of the invention. Moreover, it will be possible to practice the invention even where one or more of the intended objects and/or advantages might be absent or not required in the application.